Device and method of arthroscopic knee joint resurfacing

ABSTRACT

A knee joint resurfacing implant is disclosed. The knee joint resurfacing implant may include femoral implant and tibial implant components. The femoral implant components may be attached to the femur using screws or other fixation devices. The femoral implant component may be configured to share loads between cortical and cancellous bone material. The tibial implant components are formed in modular portions which may be assembled within the knee joint and may be free-floating or fixed to the tibial surface. The implant components are of such a size and configuration that the components may be placed into the knee joint through an external skin incisions that measure 3 cm or less. Accordingly, the size of skin incisions required for implantation may be reduced when compared to incisions which are now commonly used.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims-priority from provisional patent applicationSer. No 60/532,537, filed with the United States Patent and Trademarkoffice on Dec. 23, 2003. The entire teachings of the said applicationare incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

REFERENCE TO MICROFICHE APPENDIX

Not Applicable.

BACKGROUND OF THE INVENTION

The present disclosure relates generally to knee replacement implants,and more particularly, but not necessarily entirely, to arthroscopicknee replacement implants for the femur and tibia.

It is common to provide implants to resurface worn articular surfaces ofknees. The sizes of incisions required to insert the implants are oftenrelatively large. Moreover, the prior art is characterized by severalother disadvantages that are addressed by the present disclosure. Theinvention of the present disclosure minimizes, and in some aspectseliminates, numerous failures of the prior art, and other problems, byutilizing the devices described herein.

BRIEF SUMMARY OF THE INVENTION

A knee joint resurfacing implant including femoral and tibial implantcomponents is disclosed. The femoral implant component includes an apexand supports on the proximal surface which are configured to share loadsbetween cortical and cancellous bone material when the femoral implantcomponent is implanted on the distal end of a prepared femur. Thefemoral implant may be attached to the femur using screws or other rigidmembers such as a peg, pin, or stem that traverses the externalarticulating surface and has a terminal surface that uniformly matchesthe external articulating surface of the implant. The tibial implantcomponent of the knee replacement implant has a semicircularcircumference, a concave superior surface, a planar inferior surface,and is divided into medial and lateral halves by a joint runninglongitudinally through the implant. The tibial implant component may beassembled within the knee joint. Accordingly, the femoral and tibialimplant components may be configured and sized to be implanted using anarthroscopic surgical techniques and to permit the reduction of the sizeof skin incisions required for implantation.

The features and advantages of the disclosure will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by the practice of the disclosure withoutundue experimentation. The features and advantages of the disclosure maybe realized and obtained by means of the instruments and combinationsparticularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the disclosure will become apparent froma consideration of the subsequent detailed description presented inconnection with the accompanying drawings in which:

FIG. 1 is a front view of a femoral implant in accordance with theprinciples of the present disclosure;

FIG. 2 is a side view of the femoral implant of FIG. 1;

FIG. 3 is a cross-sectional view of the femoral implant taken alongsection A-A of FIG. 2;

FIG. 4 is a top view of a tibial implant;

FIG. 5 is a side view the tibial implant of FIG. 4, as viewed from thelateral side;

FIG. 6 is an end view of the tibial implant of FIG. 4; and

FIG. 7 is an exploded side view of a knee, including a femur, tibia, andpatella, in which the femoral and tibial implants are installed.

DETAILED DESCRIPTION OF THE INVENTION

For the purposes of promoting an understanding of the principles inaccordance with the disclosure, reference will now be made to theembodiments illustrated in the drawings and specific language will beused to describe the same. It will nevertheless be understood that nolimitation of the scope of the disclosure is thereby intended. Anyalterations and further modifications of the inventive featuresillustrated herein, and any additional applications of the principles ofthe disclosure as illustrated herein, which would normally occur to oneskilled in the relevant art and having possession of this disclosure,are to be considered within the scope of the disclosure claimed.

In describing and claiming the present disclosure, the followingterminology will be used in accordance with the definitions set outbelow.

As used herein, the terms “comprising,” “including,” “containing,”“characterized by,” and grammatical equivalents thereof are inclusive oropen-ended terms that do not exclude additional, unrecited elements ormethod steps.

Referring now to FIG. 1, a front view of a femoral implant 10 is shown.The femoral implant 10 may have one or more screw receiving holes 12 forreceiving a screw 14 for attaching the femoral implant 10 to the distalend of the femur, as shown most clearly in FIG. 7. As shown in FIG. 3,which shows a cross-sectional view of the femoral implant 10 taken alongthe line A-A in FIG. 2, the femoral implant 10 may include a curvedsurface 16 configured for contacting a tibial implant 22 as shown inFIG. 7. The femoral implant 10 may also include an apex portion 18 andsupports 20 to engage the prepared distal end of the femur. The apexportion 18 may be configured to be received in the cancellous bonematerial of the femur, whereas the supports 20 may be configured tocontact the cortical bone material of the femur, so that load sharingbetween the cortical bone and the cancerous bone may be accomplished.

The femoral implant 10 may be used to repair a single condyle, referredto as a unicondylar replacement. Also, two femoral implants 10 may beused in a bi-condylar replacement within the scope of the presentdisclosure.

The femoral component 10 may be shaped to reproduce the weight bearingarticular surface of the knee. The femoral component 10 may beconfigured to be 15-20 mm in width, for example, with an anatomicalassortment of lengths and thicknesses. It will be understood that otherwidths and dimensions may be used within the scope of the presentdisclosure. Moreover, it will be understood that the femoral implant 10may be implanted without resurfacing the entire width of the condyle.Accordingly, the femoral implant 10 may form a narrow rim on the condylewhich may cooperate with the remaining portion of the condyle. Thefemoral component 10 may be made of a high molecular weight polyethylene(HMWPE) or any other suitable material known to those skilled in theart.

The screw receiving holes 12 may be formed of two distinct dimensions,as shown most clearly in FIG. 2, to allow for a cancellous type of screwto pass in order to provide fixation to the femur, with or withoutpolymethylmethacrylate (PMMA) cement.

As shown in FIGS. 4-7, the tibial implant component 22 may be formedhaving a semicircular circumference. The tibial implant component 22 mayhave a concave superior surface 24 and a planar inferior surface 26. Thetibial implant component 22 may be divided into a medial portion 28 anda lateral portion 30 by an implant joint 32. The implant joint 32 mayallow the tibial implant component 22 to be inserted into the knee jointin separate pieces through an arthroscopic portal and then assembledwithin the knee joint at the time of implantation under arthroscopicvisualization. It will be understood that the implant joint 32 may be inthe form of a dovetailed joint with a projection 34 on the lateralportion 30 and a channel 36 on the medial portion 28, or the projection34 may be formed on the medial portion 28 and the channel 36 may be onthe lateral portion 30. It will also be appreciated that other types ofjunctions or interlocking geometric interfaces may be used within thescope of the present disclosure. Moreover, the implant joint 32 may beself locking and may include any of a variety of fasteners or attachingdevices to prevent the medical portion 28 and the lateral portion 30from becoming separated.

It will be understood that the tibial implant 22 may be formed of metal,polymer, or any other suitable material known to those skilled in theart.

The tibial implant component 22 may be attached to the tibia to preventmigration of the tibial implant component 22 with respect to the tibia,or the tibial implant component 22 may be free floating on the tibia.The tibial implant component 22 may be cemented in place using an accesschannel 38 passing obliquely from the anterior proximal tibia into thecentral aspect of the tibial plateau as illustrated in FIG. 7. Theaccess channel 38 allows cement to be placed on the tibial implant 22 ina manner to avoid unwanted spreading of the cement. Moreover, a strandor other tensioning device may optionally be placed in the accesschannel 38 and attached to the tibial implant component 22 by anysuitable means. The strand may be a suture or any other mechanism knownto those skilled in the art. Similarly, any variety of cement known tothose skilled in the art may be installed through the access channel 38.

As shown in FIG. 7, which shows an exploded side view of a knee,including the femur, tibia and patella, in which the femoral implantcomponent 10 and tibial implant component 22 are implanted, the convexcurved surface 16 of the femoral implant component 10 may be configuredto fit in the concave superior surface 24 of the tibial implantcomponent 22. The inferior surface 26 of the tibial implant component 22as shown in FIG. 5 is configured to mate to the proximal surface of thetibia as shown in FIG. 7, and the superior surface 24 of the tibialimplant component 22 is configured to mate and articulate with thedistal convex curved surface 16 of the femoral component 10 in aconformational relationship. Thus, the size and shape of the tibialimplant 22 and femoral implant 10 and their articulating surfaces mayvary to conform to a desired anatomical structure. In one embodiment ofthe tibial implant 22, the tibial implant 22 may be thicker on themedial side 28 than on the lateral side 30.

Orientation of the mechanical axis of the knee joint, and the depth andposition of cuts made to the native surface of the knee prior to implantinsertion may be facilitated by the use of a surgical navigation systemthat may include immediate real time data acquisition and retrieval.

The present disclosure provides surgeons and patients with a reliableand technical method and implants to appropriately resurface the wornarticular surface of a single knee compartment. The design of theinstruments and implants may allow skin incisions to be less than 25 mmin length. The procedure may be performed arthroscopically with surgicalnavigational assist.

In the foregoing, various features of the present disclosure are groupedtogether in a single embodiment for the purpose of streamlining thedisclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed disclosure requires morefeatures than are expressly recited in each claim. Rather, as the claimswill reflect, inventive aspects lie in less than all features of asingle foregoing disclosed embodiment.

It is to be understood that the above-described arrangements are onlyillustrative of the application of the principles of the presentdisclosure. Numerous modifications and alternative arrangements may bedevised by those skilled in the art without departing from the spiritand scope of the present disclosure and the appended claims are intendedto cover such modifications and arrangements. Thus, while the presentdisclosure has been shown in the drawings and described above withparticularity and detail, it will be apparent to those of ordinary skillin the art that numerous modifications, including, but not limited to,variations in size, materials, shape, form, function and manner ofoperation, assembly and use may be made without departing from theprinciples and concepts set forth herein.

1. An implant to resurface a femoral condyle of the knee jointcomprising a femoral body that has a distal, convex surface forarticulation with the tibial side of the joint and a proximal surfacethat has an apex for engagement with the distal end of a prepared femur.2. The implant of claim 1 wherein the profile of the distal, convexsurface closely approximates the radius of curvature of the articulatingsurface of a native femoral condyle in the sagital plane.
 3. The implantof claim 1 wherein fixation of the implant to the femur is provided byone or more screws that are inserted in one or more screw receivingholes that traverse the implant through the femoral body from thedistal, convex surface to the proximal surface.
 4. The implant of claim1 wherein fixation is provided by one or more rigid fixation members,such as a screws, pegs, pins or stems, that are inserted in one or morescrew receiving holes that traverse the implant through the femoral bodyfrom the distal, convex surface to the proximal surface and thattraverse the external articulating surface and have a terminal surfaceprofile that uniformly matches the distal, convex articulating surfaceof the implant such that when fully seated the terminal surface of saidfixation members is flush or congruent with the external articulatingsurface of the implant.
 5. The implant of claim 1 wherein the implant isformed from a biologically compatible metal, polymer, biologic,allograft, or xenograft material.
 6. The implant of claim 1 whereinfixation of the implant to the femur is augmented by bone cement oradhesive that is be placed between the implant and the femur.
 7. Theimplant of claim 1 wherein the implant is of such a size andconfiguration that it may be placed into the knee joint through anexternal skin incision that measures 3 cm or less.
 8. The implant ofclaim 1 wherein the implant may be implanted using an arthroscopicvisualization method.
 9. An implant to resurface a femoral condyle ofthe knee joint comprising a femoral body that has a distal, convexsurface for articulation with the tibial side of the joint and aproximal surface that has an apex for engagement with cancellous bone ofthe distal end of a prepared femur and one or more supports forengagement with cortical bone of the distal end of a prepared femur. 10.The implant of claim 9 wherein the profile of the distal, convex surfaceclosely approximates the radius of curvature of the articulating surfaceof a native femoral condyle in the sagital plane.
 11. The implant ofclaim 9 wherein fixation of the implant to the femur is provided by oneor more screws that are inserted in one or more screw receiving holesthat traverse the implant through the femoral body from the distal,convex surface to the proximal surface.
 12. The implant of claim 9wherein fixation is provided by one or more rigid fixation members, suchas a screws, pegs, pins or stems, that are inserted in one or more screwreceiving holes that traverse the implant through the femoral body fromthe distal, convex surface to the proximal surface and that traverse theexternal articulating surface and have a terminal surface profile thatuniformly matches the distal, convex articulating surface of the implantsuch that when fully seated the terminal surface of said fixationmembers is flush or congruent with the external articulating surface ofthe implant.
 13. The implant of claim 9 wherein the implant is formedfrom a biologically compatible metal, polymer, biologic, allograft, orxenograft material.
 14. The implant of claim 9 wherein fixation of theimplant to the femur is augmented by bone cement or adhesive that is beplaced between the implant and the femur.
 15. The implant of claim 9wherein the implant is of such a size and configuration that it may beplaced into the knee joint through an external skin incision thatmeasures 3 cm or less.
 16. The implant of claim 9 wherein the implantmay be implanted using an arthroscopic visualization method.
 17. Animplant to resurface a femoral condyle of the knee joint comprising afemoral body that has a distal, convex surface with a profile thatclosely approximates the radius of curvature of the articulating surfaceof a native femoral condyle in the sagital plane for articulation withthe tibial side of the joint and that has a proximal surface with anapex for engagement with cancellous bone of the distal end of a preparedfemur and one or more supports for engagement with cortical bone of thedistal end of a prepared femur.
 18. The implant of claim 17 whereinfixation of the implant to the femur is provided by one or more screwsthat are inserted in one or more screw receiving holes that traverse theimplant through the femoral body from the distal, convex surface to theproximal surface.
 19. The implant of claim 17 wherein fixation isprovided by one or more rigid fixation members, such as screws, pegs,pins or stems, that are inserted in one or more screw receiving holesthat traverse the implant through the femoral body from the distal,convex surface to the proximal surface and that traverse the externalarticulating surface and have a terminal surface profile that uniformlymatches the distal, convex articulating surface of the implant such thatwhen fully seated the terminal surface of said fixation members is flushor congruent with the external articulating surface of the implant. 20.The implant of claim 17 wherein the implant is formed from abiologically compatible metal, polymer, biologic, allograft, orxenograft material.
 21. The implant of claim 17 wherein fixation of theimplant to the femur is augmented by bone cement or adhesive that is beplaced between the implant and the femur.
 22. The implant of claim 17wherein the implant is of such a size and configuration that it may beplaced into the knee joint through an external skin incision thatmeasures 3 cm or less.
 23. The implant of claim 17 wherein the implantmay be implanted using an arthroscopic visualization method.
 24. Animplant to resurface a femoral condyle of the knee joint comprising afemoral body that has a distal, convex surface with a profile thatclosely approximates the radius of curvature of the articulating surfaceof a native femoral condyle in the sagital plane for articulation withthe tibial side of the joint and that has a proximal surface with anapex for engagement with cancellous bone of the distal end of a preparedfemur and one or more supports for engagement with cortical bone of thedistal end of a prepared femur and where the fixation of the implant tothe femur is provided by one or more screws that are inserted in one ormore screw receiving holes that traverse the implant through the femoralbody from the distal, convex surface to the proximal surface and theimplant is formed from a biologically compatible metal, polymer,biologic, allograft, or xenograft material.
 25. The implant of claim 24wherein fixation of the implant to the femur is augmented by bone cementor adhesive that is be placed between the implant and the femur.
 26. Theimplant of claim 24 wherein the implant is of such a size andconfiguration that it may be placed into the knee joint through anexternal skin incision that measures 3 cm or less.
 27. The implant ofclaim 24 wherein the implant may be implanted using an arthroscopicvisualization method.
 28. An implant to resurface a femoral condyle ofthe knee joint comprising a femoral body that has a distal, convexsurface with a profile that closely approximates the radius of curvatureof the articulating surface of a native femoral condyle in the sagitalplane for articulation with the tibial side of the joint and that has aproximal surface with an apex for engagement with cancerous bone of thedistal end of a prepared femur and one or more supports for engagementwith cortical bone of the distal end of a prepared femur whereinfixation of the implant is provided by one or more rigid fixationmembers, such as screws, pegs, pins or stems, that are inserted in oneor more screw receiving holes that traverse the implant through thefemoral body from the distal, convex surface to the proximal surface andthat traverse the external articulating surface and have a terminalsurface profile that uniformly matches the distal, convex articulatingsurface of the implant such that when fully seated the terminal surfaceof said fixation members is flush or congruent with the externalarticulating surface of the implant and the implant is formed from abiologically compatible metal, polymer, biologic, allograft, orxenograft material.
 29. The implant of claim 28 wherein fixation of theimplant to the femur is augmented by bone cement or adhesive placedbetween the implant and the femur.
 30. The implant of claim 28 whereinthe implant is of such a size and configuration that it may be placedinto the knee joint through an external skin incision that measures 3 cmor less.
 31. The implant of claim 28 wherein the implant may beimplanted using an arthroscopic visualization method.
 32. An implant toresurface a femoral condyle of the knee joint comprising a femoral bodythat has a distal, convex surface with a profile that closelyapproximates the radius of curvature of the articulating surface of anative femoral condyle in the sagital plane for articulation with thetibial side of the joint and that has a proximal surface with an apexfor engagement with cancellous bone of the distal end of a preparedfemur and one or more supports for engagement with cortical bone of thedistal end of a prepared femur and where the fixation of the implant tothe femur is provided by one or more screws that are inserted in one ormore screw receiving holes that traverse the implant through the femoralbody from the distal, convex surface to the proximal surface and theimplant is formed from a biologically compatible metal, polymer,biologic, allograft, or xenograft material and wherein the implant is ofsuch a size and configuration that it may be placed into the knee jointthrough an external skin incision that measures 3 cm or less and theimplant may be implanted using an arthroscopic visualization method 33.An implant to resurface a femoral condyle of the knee joint comprising afemoral body that has a distal, convex surface with a profile thatclosely approximates the radius of curvature of the articulating surfaceof a native femoral condyle in the sagital plane for articulation withthe tibial side of the joint and that has a proximal surface with anapex for engagement with cancellous bone of the distal end of a preparedfemur and one or more supports for engagement with cortical bone of thedistal end of a prepared femur wherein fixation of the implant isprovided by one or more rigid fixation members, such as screws, pegs,pins or stems, that are inserted in one or more screw receiving holesthat traverse the implant through the femoral body from the distal,convex surface to the proximal surface and that traverse the externalarticulating surface and have a terminal surface profile that uniformlythe distal convex articulating surface of the implant such that whenfully seated the terminal surface of said fixation members is flush orcongruent with the external articulating surface of the implant and theimplant is formed from a biologically compatible metal, polymer,biologic, allograft, or xenograft material and wherein the implant is ofsuch a size and configuration that it may be placed into the knee jointthrough an external skin incision that measures 3 cm or less and theimplant may be implanted using an arthroscopic visualization method. 34.An implant to resurface the tibial condyle of the knee joint comprisinga tibial body that has a concave superior surface, a planar inferiorsurface, and divided into medial and lateral halves by a joint runninglongitudinally through the implant.
 35. The implant of claim 34 whereinthe medial and lateral halves of the tibial body may be passedseparately into the joint space of a knee joint and be assembled into asingle unit therein.
 36. The implant of claim 34 wherein the medial andlateral halves are self-locking or include a separate locking device tomaintain their attachment within the knee joint following assembly intoa single unit.
 37. The implant of claim 36 wherein the medial andlateral halves of the tibial body include complementary dovetail jointsor other geometric interface junctions to permit assembly of the halvesinto a single unit.
 38. The implant of claim 34 wherein the tibialcomponent is free floating upon the tibial surface.
 39. The implant ofclaim 35 wherein the tibial component is securely attached to the tibia.40. The implant of claim 34 wherein the tibial component is of such asize and configuration that it may be placed into the knee joint throughan external skin incision that measures 3 cm or less.
 41. The implant ofclaim 34 wherein the tibial implant component may be attached to thetibia by means placed through an oblique access channel formed throughthe tibia from the anterior tibial cortex to the central tibial condylarsurface.
 42. The implant of claim 41 wherein the tibial implantcomponent is secured to the tibia by a cement, adhesive, or biologicallyactive substance applied to the inferior tibial implant componentsurface through the oblique access channel.
 43. The implant of claim of41 wherein the tibial implant component is secured to the tibia by astrand or member that is attached to the inferior tibial implantcomponent surface and which passes into the oblique access channel. 44The implant of claim 41 wherein said strand or member extends throughthe length of the oblique access channel and exits through the openingof the oblique access channel on the anterior tibial cortex.
 45. Theimplant of claim 44 wherein the strand or member is externally attachedto the anterior tibial cortex to secure the tibial implant component tothe tibial surface.
 46. The implant of claim 45 wherein the strand ormember is under tension when said strand or member is attached to theanterior tibial cortex to secure the tibial implant component to thetibial surface.
 47. The implant of claim 41 wherein the strand or memberis a suture, cable, chain, screw, rod, bolt, loop, hook, or graspingdevice.
 48. An implant to resurface the tibial condyle of the knee jointcomprising a tibial body that has a semicircular circumference, aconcave superior surface, a planar inferior surface, and divided intomedial and lateral halves by a joint running longitudinally through theimplant.
 49. The implant of claim 48 wherein the medial and lateralhalves of the tibial body may be passed separately into the joint spaceof a knee joint and be assembled into a single unit therein.
 50. Theimplant of claim 48 wherein the medial and lateral halves areself-locking or include a separate locking device to maintain theirattachment following assembly into a single unit.
 51. The implant ofclaim 50 wherein the medial and lateral halves of the tibial bodyinclude complementary dovetail joints or other geometric interfacejunctions to permit assembly of the halves into a single unit.
 52. Theimplant of claim 48 wherein the tibial component is free floating uponthe tibial surface.
 53. The implant of claim 48 wherein the tibialcomponent is securely attached to the tibia.
 54. The implant of claim 48wherein the tibial component is of such a size and configuration that itmay be placed into the knee joint through an external skin incision thatmeasures 3 cm or less.
 55. The implant of claim 48 wherein the tibialimplant component may be attached to the tibia by means placed throughan oblique access channel formed through the tibia from the anteriortibial cortex to the central tibial condylar surface.
 56. The implant ofclaim 55 wherein the tibial implant component is secured to the tibia bya cement, adhesive, or biologically active substance applied to theinferior tibial implant component surface through the oblique accesschannel.
 57. The implant of claim of 55 wherein the tibial implantcomponent is secured to the tibia by a strand or member that is attachedto the inferior tibial implant component surface and which passes intothe oblique access channel. 58 The implant of claim 57 wherein saidstrand or member extends through the length of the oblique accesschannel and exits through the opening of the access channel on theanterior tibial cortex.
 59. The implant of claim 58 wherein the strandor member is externally attached to the anterior tibial cortex to securethe tibial implant component to the tibial surface.
 60. The implant ofclaim 59 wherein the strand or member is under tension when said strandor member is attached to the anterior tibial cortex to secure the tibialimplant component to the tibial surface.
 61. The implant of claim 55wherein the strand or member is a suture, cable, chain, screw, rod,bolt, loop, hook, or grasping device.
 62. An implant to resurface thetibial condyle of the knee joint comprising a tibial body that has aconcave superior surface, a planar inferior surface, and divided intomedial and lateral halves by a joint running longitudinally through theimplant where the medial and lateral halves of the tibial body may bepassed separately into the joint space of a knee joint and be assembledinto a single unit therein.
 63. The implant of claim 62 wherein themedial and lateral halves are self-locking or include a separate lockingdevice to maintain their attachment following assembly into a singleunit.
 64. The implant of claim 63 wherein the medial and lateral halvesof the tibial body include complementary dovetail joints or othergeometric interface junctions to permit assembly of the halves into asingle unit.
 65. The implant of claim 62 wherein the tibial component isfree floating upon the tibial surface.
 66. The implant of claim 62wherein the tibial component is securely attached to the tibia.
 67. Theimplant of claim 62 wherein the tibial component is of such a size andconfiguration that it may be placed into the knee joint through anexternal skin incision that measures 3 cm or less.
 68. The implant ofclaim 62 wherein the tibial implant component may be attached to thetibia by means placed through an oblique access channel formed throughthe tibia from the anterior tibial cortex to the central tibial condylarsurface.
 69. The implant of claim 68 wherein the tibial implantcomponent is secured to the tibia by a cement, adhesive, or biologicallyactive substance applied to the inferior tibial implant componentsurface through the oblique access channel.
 70. The implant of claim of68 wherein the tibial implant component is secured to the tibia by astrand or member that is attached to the inferior tibial implantcomponent surface and which passes into the oblique access channel. 71.The implant of claim 70 wherein said strand or member extends throughthe length of the oblique access channel and exits through the openingof the oblique access channel on the anterior tibial cortex.
 72. Theimplant of claim 71 wherein the strand or member is externally attachedto the anterior tibial cortex to secure the tibial implant component tothe tibial surface.
 73. The implant of claim 72 wherein the strand ormember is under tension when said strand or member is attached to theanterior tibial cortex to secure the tibial implant component to thetibial surface.
 74. The implant of claim 70 wherein the strand or memberis a suture, cable, chain, screw, rod, bolt, loop, hook, or graspingdevice.
 75. An implant to resurface the tibial condyle of the knee jointcomprising a tibial body that has a semicircular circumference, aconcave superior surface, a planar inferior surface, and divided intomedial and lateral halves by a joint running longitudinally through theimplant where the medial and lateral halves of the tibial body may bepassed separately into the joint space of a knee joint and be assembledinto a single unit therein.
 76. The implant of claim 75 wherein themedial and lateral halves are self-locking or include a separate lockingdevice to maintain their attachment following assembly into a singleunit.
 77. The implant of claim 76 wherein the medial and lateral halvesof the tibial body include complementary dovetail joints or othergeometric interface junctions to permit assembly of the halves into asingle unit.
 76. The implant of claim 75 wherein the tibial component isfree floating upon the tibial surface.
 77. The implant of claim 75wherein the tibial component is securely attached to the tibia.
 78. Theimplant of claim 75 wherein the tibial component is of such a size andconfiguration that it may be placed into the knee joint through anexternal skin incision that measures 3 cm or less.
 79. The implant ofclaim 75 wherein the tibial implant component may be attached to thetibia by means placed through an oblique access channel formed throughthe tibia from the anterior tibial cortex to the central tibial condylarsurface.
 80. The implant of claim 79 wherein the tibial implantcomponent is secured to the tibia by a cement, adhesive, or biologicallyactive substance applied to the inferior tibial implant componentsurface through the oblique access channel.
 81. The implant of claim of79 wherein the tibial implant component is secured to the tibia by astrand or member that is attached to the inferior tibial implantcomponent surface and which passes into the oblique access channel. 82.The implant of claim 81 wherein said strand or member extends throughthe length of the oblique access channel and exits through the openingof the oblique access channel on the anterior tibial cortex.
 83. Theimplant of claim 82 wherein the strand or member is externally attachedto the anterior tibial cortex to secure the tibial implant component tothe tibial surface.
 84. The implant of claim 83 wherein the strand ormember is under tension when said strand or member is attached to theanterior tibial cortex to secure the tibial implant component to thetibial surface.
 85. The implant of claim 81 wherein the strand or memberis a suture, cable, chain, screw, rod, bolt, loop, hook, or graspingdevice.
 86. A knee replacement implant comprising: a femoral implantcomponent to resurface a femoral condyle of the knee joint that has acurved convex surface for articulation with the tibial side of the jointand the opposite surface composed of an apex for engagement with aprepared femur; and a tibial implant component implant to resurface thetibial condyle of the knee joint that has a semicircular circumference,a concave superior surface, a planar inferior surface, and divided intomedial and lateral halves by a joint running longitudinally through theimplant.
 87. The knee replacement implant of claim 86 wherein theopposite surface of the femoral implant component also includes one ormore supports.
 88. The knee replacement implant of claim 86 wherein themedial and lateral halves of the tibial implant component may be passedseparately into the joint space of a knee joint and there be assembledinto a single unit.
 89. The knee replacement implant of claim 86 whereinthe opposite surface of the femoral implant component also includes oneor more supports and the medial and lateral halves of the tibial implantcomponent may be passed separately into the joint space of a knee jointand there be assembled into a single unit.
 90. The knee replacementimplant of claim 89 wherein the size and configuration of the femoralimplant component and of the medial and lateral halves of the tibialimplant component are such that they may be placed into the knee jointthrough an external skin incision that measures 3 cm or less.
 91. Theknee replacement implant of claim 86 wherein the tibial implantcomponent may be attached to the tibia by means placed through anoblique access channel formed through the tibia from the anterior tibialcortex to the central tibial condylar surface.
 92. The implant of claim91 wherein the tibial implant component is secured to the tibia by acement, adhesive, or biologically active substance applied to theinferior tibial implant component surface through the oblique accesschannel.
 93. The implant of claim of 91 wherein the tibial implantcomponent is secured to the tibia by a strand or member that is attachedto the inferior tibial implant component surface and which passes intothe oblique access channel.
 94. The knee replacement implant of claim 91wherein the size and configuration of the femoral implant component andof the medial and lateral halves of the tibial implant component aresuch that they may be placed into the knee joint through an externalskin incision that measures 3 cm or less.